Method for Indicating Shelf-Life After Mixing Pre-Dosed, Pre-Packaged Two-Part Dental Compositions

ABSTRACT

A pre-dosed, pre-packaged mixing system and associated method for mixing, storing, and dispensing a two-part dental composition that becomes less stable upon mixing. The mixing system includes a pre-dosed, pre-packaged quantity of a first component contained within a first chamber, and a pre-dosed, pre-packaged quantity of a second component contained within a second chamber. The chambers are separated by separation means so as to separate the two-components prior to mixing. Once mixed, the practitioner is able to record a mixing and/or expiration date on at least a portion of the mixing system so as to indicate a shelf-life of the less stable mixed dental composition.

RELATED APPLICATIONS

The present application is a Continuation of U.S. patent applicationSer. No. 11/537,807, filed Oct. 2, 2006 entitled METHOD FOR INDICATINGSHELF-LIFE AFTER MIXING PRE-DOSED, PRE-PACKAGED TWO-PART DENTALCOMPOSITIONS, and a continuation-in-part of U.S. patent application Ser.No. 11/258,502, filed Oct. 25, 2005 and entitled “TIME INDICATINGCONTAINERS FOR DENTAL COMPOSITIONS, now abandoned, and acontinuation-in-part of U.S. patent application Ser. No. 11/414,964,filed May 1, 2006 and entitled “TIME-INDICATING SYRINGE-IN-SYRINGEMIXING DEVICES AND RELATED METHODS FOR STORING AND DISPENSING TWO-PARTDENTAL COMPOSITIONS, now abandoned, all of which are incorporated byreference in their entirety.

BACKGROUND OF THE INVENTION

1. The Field of the Invention

In one aspect, the present invention is directed to devices for holdingand dispensing dental compositions. More particularly, in one aspect,the invention is directed to containers for holding and dispensingdental compositions having a given shelf-life after which thecomposition should either be used up or discarded. For example, manymulti-part dental compositions require mixing of two separatecomponents, the mixed composition having a particular shelf-life, afterwhich time the mixed composition should be used up or discarded. Anotheraspect of the invention is related to methods for mixing suchcompositions and indicating shelf-life of the resulting compositions.

2. The Relevant Technology

Many modern formulations are packaged in two initially separate parts,often known as A and B components. Upon mixing, the A and B componentsform a mixed composition having a particular viable shelf-life, afterwhich the composition should be used up or discarded. In the dentalfield, for example, several such formulations include two-part dentalprimers, peroxide and other two-part bleaching compositions, anddisinfecting solutions.

It can be difficult for a dental practitioner to determine whether theshelf-life of a formulation has expired, or how much of theformulation's shelf-life remains. This difficulty can be furthercomplicated in some instances where the shelf-life of a givenformulation may depend on the environment in which the formulation isstored. For example, many formulations may have an extended shelf-lifeif stored in a refrigerated environment as compared to the shelf-lifewhen stored at room temperature.

Furthermore, when mixing a two-part composition it is necessary tomeasure needed amounts of each component. In addition to being tedious,even small variations in measurement of one component relative toanother component may drastically affect the actual shelf-life of themixed composition because of errors in the mixing ratio of thecomponents.

It would be an advantage to provide a container system for use with sucha formulation that would allow the user to quickly and easily determinehow much time remains of the shelf-life of a given formulation. It wouldbe a further advantage if such a system could account for variability inshelf-life due to changes in the formulation storage environment. Itwould be a further advantage to provide a simple method that wouldindicate remaining shelf-life of a composition, and that would eliminatevariability in actual shelf-life due to errors in measuring neededquantities of the components.

SUMMARY OF THE INVENTION

In one aspect, the present invention is directed to a storage system fora dental composition having a given shelf-life. The storage systemincludes a container (e.g., a syringe), and activatable time sensitivemarking means disposed on or within the container, wherein uponactivation, the time sensitive marking means identifies time lapsedsince activation of the time sensitive marking means. The dentalpractitioner may activate the time sensitive marking means at anappropriate time to monitor the shelf-life of the dental composition(e.g., immediately after preparing the composition by mixing togetherinitially separate components). The time sensitive marking means allowsa dental practitioner to determine whether a dental composition withinthe container has expired, or how much time remains before thecomposition expires and should either be used up or discarded.

In one example, the activatable time sensitive marking means comprisesan activatable label disposed on or within the container. One such labelincludes a length of a microporous material and a tinted liquid thatmigrates along the microporous material by capillary action so as tohave a migration length that increases as a function of time. The labelis activated by causing the tinted liquid to contact the microporousmaterial. In one example, the tinted liquid may initially be containedwithin a blister or similar packaging adjacent to the microporousmaterial. Upon pressing (i.e., activating) the blister packaging, thetinted liquid contacts the microporous material and begins to wick upalong the microporous material due to capillary action. The progress ofthe tinted liquid is a function of time, such that the migration lengthof the tinted liquid indicates how much time has lapsed since activation(and thus also the time remaining until the shelf-life of thecomposition expires).

In another example, the activatable time sensitive marking means maycomprise a label including two adjacent blister packets, each blisterpacket containing a composition such that the compositions are initiallyseparate from each other. The user presses one or both of the blistersso as to cause a thin membrane between the blister packets to break,which allows the two compositions to mix together, activating the label.The mixed composition begins as characterized by having a first color,and progressively changes to a second color as a function of time. Oncethe mixed composition has changed to the second color, this indicates tothe user that the given shelf-life of a dental composition within thecontainer has expired and should be discarded.

Another activatable time sensitive marking means may comprise a tapeformed of a material that begins to change color from a first color to asecond color as a function of time. Once the tape has changed to thesecond color, this indicates to the user that the given shelf-life of adental composition within the container has expired.

Another activatable time sensitive marking means may comprise a labelincluding a microchip configured to measure lapsed time. The microchipis readable by an associated microchip reader so as to indicate to auser how much time remains of a given shelf-life of a composition withinthe container.

The activatable time sensitive marking means may be temperaturesensitive in addition to being time sensitive. Temperature sensitivityof the marking means allows the system to account for variability inshelf-life due to temperature changes in the storage environment of thedental composition stored within the container.

A dental composition within the container may have a given shelf-liferanging from less than about a week to 2 years or more. Because ofrelative instability, many mixed two-part dental compositions have arelatively short shelf-life (e.g., 30 days or less). For example sometwo-part peroxide bleaching compositions may have a shelf-life of about10-14 days after mixing, some disinfecting solutions may have ashelf-life of about a week or less, and some two-part dental primers mayhave a shelf life of about 30 days. Relatively stable single part dentalcompositions may have a longer shelf-life (e.g., from 6 months up to 2years or more). Such compositions often include an expiration datestamped or printed on the container, which can be difficult to identify.The time sensitive marking means of the present invention provides amore easily identifiable label, eliminating the need for the user tosearch for a difficult to find date stamp.

In another aspect, the present invention is directed to a pre-dosed,pre-packaged mixing solution that includes the two-components in aninitially separate configuration, and an associated method in which thedental practitioner is able to record a mixing and/or expiration date ofthe less stable mixed composition on the mixing system itself. Themixing system includes a pre-dosed, pre-packaged quantity of a firstcomponent contained within a first chamber, and a pre-dosed,pre-packaged quantity of a second component contained within a secondchamber. The chambers are separated by separation means so as toseparate the two-components prior to mixing. Once mixed, thepractitioner is able to record a mixing and/or expiration date on atleast a portion of the mixing system so as to indicate the shelf-life ofthe less stable mixed composition.

Providing a pre-dosed, pre-packaged mixing system advantageouslyeliminates any need for the dental practitioner to measure the requiredquantities of each component prior to preparing the two-partcomposition. In addition to being convenient, because the pre-dosing isdone during manufacture, it is advantageously accomplished with agreater degree of precision and accuracy than possible in the dentaloffice environment. This reduces or eliminates the possibility ofmistakes or errors in the measured quantities of each component, whichaffects the mixing ratio of the two components. This is particularlyhelpful as errors in the mixing ratio may drastically affect the actualshelf-life of the mixed composition. For example, a mixed dental primingcomposition may have a nominal shelf-life of about 30 days after mixing,but because of a small error (e.g., ±10%) in mixing ratio, the actualshelf-life of the composition may be greatly reduced (e.g., to less than15 days). If the composition is used after its actual expiration datebut before the nominal expiration date, the composition will beineffective, resulting in waste and frustration to the dentalpractitioner and patient. In other words, the indicated expiration dateis much more meaningful in the context of a pre-dosed, pre-packagedmixing system as compared to any other system where individualmeasurement of one or more of the components is required.

These and other benefits, advantages and features of the presentinvention will become more full apparent from the following descriptionand appended claims, or may be learned by the practice of the inventionas set forth hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

In order that the manner in which the above recited and other benefits,advantages and features of the invention are obtained, a more particulardescription of the invention briefly described above will be rendered byreference to specific embodiments thereof which are illustrated in theappended drawings. Understanding that these drawings depict only typicalembodiments of the invention and are not therefore to be consideredlimiting of its scope, the invention will be described and explainedwith additional specificity and detail through the use of theaccompanying drawings in which:

FIG. 1A is a perspective view of an exemplary time indicating system forcontaining a dental composition including a syringe and an activatabletime sensitive label disposed on the syringe plunger stem;

FIG. 1B is a perspective view of another exemplary time indicatingcontainer system including a syringe and an activatable time sensitivelabel disposed on the syringe barrel;

FIG. 1C is a perspective view of another exemplary time indicatingcontainer system including a syringe and an activatable time sensitivelabel disposed on the syringe barrel flange;

FIG. 1D is a perspective view of another exemplary time indicatingcontainer system including a syringe and an activatable time sensitivelabel disposed on the head of the plunger stem;

FIG. 1E is a perspective view of another exemplary time indicatingcontainer system including a syringe and an activatable time sensitivelabel disposed at least partially within the plunger stem of thesyringe;

FIG. 2 illustrates a time indicating container system including asyringe and an activatable time sensitive label having two blisterpackets for forming a color changing composition;

FIG. 3 illustrates a time indicating container system including asyringe and a color changing tape disposed on the syringe barrel;

FIG. 4 illustrates a time indicating container system including asyringe and an activatable label including a machine readable timemonitoring microchip;

FIG. 5A illustrates an exemplary pre-dosed, pre-packagedsyringe-in-syringe mixing system for use in an exemplary method of thepresent invention;

FIG. 5B illustrates a perspective view of the second hollow plunger ofthe syringe-in-syringe mixing system of FIG. 5A;

FIG. 5C illustrates a cross-sectional view of a portion of the secondhollow plunger of the syringe-in-syringe mixing system of FIG. 5B, thecross-section taken along line 5C-5C;

FIG. 6 illustrates an alternative pre-dosed, pre-packagedsyringe-to-syringe mixing system for use in an exemplary method of thepresent invention;

FIG. 7A illustrates the exemplary pre-dosed, pre-packagedsyringe-in-syringe mixing system of FIG. 5A prior to mixing;

FIG. 7B illustrates the mixing system of FIG. 7A when the first plungeris pressed in so as to break the rupturable membrane, causing mixing ofthe two components;

FIG. 7C illustrates the mixing system of FIG. 7B once the first plungeris fully inserted into the second hollow plunger, and a mixing and/orexpiration date has been written on an exterior surface of the syringebarrel; and

FIG. 7D illustrates the mixing system coupled to a dispensing tip and aportion of the less stable mixed dental composition being dispensed ontoa surface for use.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS I. Introduction

A detailed description of the invention will now be provided withspecific reference to figures illustrating various exemplaryembodiments. It will be appreciated that like structures will beprovided with like reference designations.

In one aspect, the present invention is directed to a storage system fordental compositions having a given shelf-life. The storage systemincludes a container (e.g., a syringe) and an activatable time sensitivemarking means disposed on or within the container. Upon activation, thetime sensitive marking means begins to indicate time lapsed sinceactivation of the time sensitive marking means. The dental practitionermay activate the time sensitive marking means at an appropriate time toallow the dental practitioner to monitor the shelf-life of the dentalcomposition (e.g., immediately subsequent to preparing the compositionby mixing together initially separate components, exposing the dentalcomposition to air, or exposing the dental composition to light). Thetime sensitive marking means allows a dental practitioner to determinewhether a dental composition within the container has expired, or howmuch time remains before the composition expires and should be used upor discarded. The container and activatable time sensitive marking meansmay be relatively inexpensive, allowing the user to discard the entiresystem once the dental composition has expired.

In another aspect, the present invention is directed to a pre-dosed,pre-packaged mixing solution that includes the two-components in aninitially separate configuration, and an associated method in which thedental practitioner is easily able to record a mixing and/or expirationdate of the mixed, less stable dental composition on the mixing systemitself. The mixing system includes a pre-dosed, pre-packaged quantity ofa first component contained within a first chamber, and a pre-dosed,pre-packaged quantity of a second component contained within a secondchamber. The chambers are separated by separation means so as toseparate the two-components prior to mixing. Once mixed, thepractitioner is able to record a mixing and/or expiration date on atleast a portion of the mixing system so as to indicate when a shelf-lifeof the less stable mixed composition expires.

II. Exemplary Dental Composition Container Systems

FIG. 1A illustrates an exemplary system 100 for both containing anddispensing a dental composition 102. System 100 includes a syringe 104and an activatable time sensitive label 106. Syringe 104 includes abarrel 114 and a plunger 116. Barrel 114 includes a flange 118 andplunger 116 includes a head 120. Label 106 includes a length of amicroporous material 108 and a tinted liquid 110 that is initiallycontained within a blister 112. In the illustrated system, label 106includes a hole through which the plunger 116 of syringe 104 passes.Label 106 may be adhered to flange 118 of syringe 104 or may slide withplunger 116.

Label 106 is activated by causing the tinted liquid to contact themicroporous material. In one example, the tinted liquid may initially becontained within a blister or similar packaging adjacent to themicroporous material. Upon pressing (i.e., activating) the blisterpackaging, the tinted liquid contacts the microporous material andbegins to wick up along the microporous material due to capillaryaction. The progress of the tinted liquid is a function of time, suchthat the migration length of the tinted liquid (i.e., how far along themicroporous material the tinted liquid has migrated) indicates how muchtime has lapsed since activation (and thus also the time remaining untilthe shelf-life of the composition expires). As illustrated, microporousmaterial 108 may include markings spaced along its length to mark howmuch time has lapsed since activation (e.g., a number of days, weeks, ormonths) when the tinted liquid reaches the corresponding mark. One suchactivatable label including a microporous material and a tinted liquidinitially contained within a blister that may be suitable is availablefrom Timestrip Ltd., located in Hitchin, Hertfordshire, United Kingdom.

FIG. 1B illustrates an alternative system 100′ including a syringe 104containing a dental composition 102 and a label 106 adhered to thebarrel 114 of syringe 104. Label 106 includes a length of a microporousmaterial 108 and a tinted liquid 110 that is initially contained withina blister 112. Upon pressing (i.e., activating) blister 112, the tintedliquid 110 is brought into contact with the microporous material 108 andbegins to wick up along the microporous material 108 due to capillaryaction. The progress of the tinted liquid 110 indicates how much timehas lapsed since activation.

FIG. 1C illustrates an alternative system 200 including a syringe 204containing a dental composition 202 and a label 206 adhered to flange218 of syringe barrel 214. Label 206 includes a length of a microporousmaterial 208 and a tinted liquid 210 that is initially contained withina blister 212. Upon pressing (i.e., activating) blister 212, the tintedliquid 210 is brought into contact with the microporous material 208 andbegins to wick up along the microporous material 208 due to capillaryaction. The progress of the tinted liquid 210 indicates how much timehas lapsed since activation.

FIG. 1D illustrates an alternative system 300 including a syringe 304containing a dental composition 302. Syringe 304 includes a barrel 314and a plunger 316. A label 306 is disposed on head 320 of plunger 316.Label 306 includes a curved length of microporous material 308 and atinted liquid 310 that is initially contained within blister 312. Asubstantially straight length of microporous material may alternativelybe used. In addition, a curved length of microporous material 308 mayalso be used with any of the other illustrated embodiments. Such acurved length of microporous material 308 may be particularly suited forthe embodiment of FIG. 1C.

Again referring to FIG. 1D, locating blister 312 on head 320 makes itconveniently placed for activation as plunger 316 is also used todispense composition 302. Blister 312 can be pressed, forcing tintedliquid 310 into contact with an end of the curve of microporous material308. Liquid 310 begins to wick up, progressing along microporousmaterial 308 due to capillary action. The progress of the tinted liquid310 indicates how much time has lapsed since activation under givenconditions (e.g., room temperature).

FIG. 1E illustrates an alternative system 300′ including a syringe 304′containing a dental composition 302. Syringe 304′ includes a barrel 314and a plunger stem 316′. A label 306′ is disposed at least partiallywithin plunger 316′. Label 306′ includes a length of microporousmaterial 308′ that is sealed within plunger stem 316′. Microporousmaterial 308′ is arranged so as to be along or parallel to the centrallongitudinal axis of plunger stem 316′. A tinted liquid 310′ isinitially contained within blister 312′ disposed on head 320′. Blister312′ can be pressed, forcing tinted liquid 310′ into contact with an endof microporous material 308′. Liquid 310′ begins to wick up, progressingalong microporous material 308′ due to capillary action. The progress ofthe tinted liquid 310′ indicates how much time has lapsed sinceactivation under given conditions (e.g., room temperature). Sealingmicroporous material 308′ within plunger stem 316′ provides a controlledhumidity environment for microporous material 308′, which can provideincreased accuracy when used in both dry and humid environments wherehumidity may not be constant. This is because the rate of progress alongthe microporous material due to capillary action can be affected bychanges in humidity.

Labels 106, 206, 306, and 306′ are examples of activatable timesensitive marking means. Because the labels rely on capillary action ofa liquid migrating through a microporous material, the rate of migrationof the tinted liquid may be dependent on temperature in addition totime. In other words, the tinted liquid may migrate a given distance(e.g., about the distance marked “7 days”) over a seven day period whenstored at room temperature, but may alternatively migrate a shorterdistance (e.g., about the distance marked “3 days”) if stored in arefrigerated environment (e.g., as a result of increased viscosity ofthe tinted liquid and/or decreased wetting ability of the microporousmaterial). Surprisingly, it has been found that the temperaturedependent variability of the capillary action roughly matches thetemperature dependent variability of the shelf-life of many dentalcompositions. For example, the dental composition may be stored in arefrigerated environment, and then later stored at room temperature, andthe progress of the tinted liquid along the microporous material mayvary according to the environment conditions. This characteristic isadvantageous as it allows the label to accurately indicate the remainingshelf-life of a dental composition that varies due to differences instorage environments.

FIG. 2 illustrates an alternative system 400 including a syringe 404containing a dental composition 402. Syringe 404 includes a barrel 414and a plunger 416. A label 406 is disposed on barrel 414. Label 406includes a first blister 422 and a second blister 424 near first blister422. First blister 422 contains a first composition and second blister424 contains a different second composition. Blisters 422 and 424 areinitially separated by a thin membrane. In order to activate timesensitive label 406, the user presses one or both of blisters 422 and424 so as to break the thin membrane and cause the compositions to mixtogether. The mixed composition begins as a first color andprogressively changes to a second different color over time. As long asthe mixed composition is not of the second color, the user knows thatthe dental composition within with container has not yet expired. Oncethe second color has been reached, the dental composition 402 or system400 should be discarded. In some embodiments, the mixed composition mayinclude one or more intermediate colors between the initial color andthe second color that signifies expiration of the dental composition.One such label including blisters containing initially separatecomponents for forming a color changing mixed composition that may besuitable is available from Vitsab Inc., located in Belmont, N.C.

Because label 406 relies on a color changing chemical reaction, the rateof reaction may also be dependent on temperature. Surprisingly, it hasbeen found that the temperature dependent variability of the colorchanging chemical reaction roughly matches the temperature dependentvariability of the shelf-life of many dental compositions. Thischaracteristic is advantageous as it allows the label to accuratelyindicate the remaining shelf-life of a dental composition that variesdue to differences in storage environments.

FIG. 3 illustrates an alternative system 500 including a syringe 504containing a dental composition 502. Syringe 504 includes a barrel 514and a plunger 516. A label 506 is disposed on barrel 514. Label 506 isformed of a material that begins to change color from a first color to asecond color as a function of time. After activation, as long as label506 is not of the second color, the user knows that the dentalcomposition 502 within container 504 has not yet expired. Once thesecond color has been reached, the dental composition 502 or system 500should be discarded. In some embodiments, the label 506 may changecolors so as to include one or more intermediate colors between theinitial color and the second color that signifies expiration of thedental composition. One such label formed of a color changing materialthat may be suitable is available from Wipak UK Ltd., located inWelshpool, Powys, United Kingdom.

Label 506 may be activated by exposure of the material to moisturewithin the air. As such, label 506 may initially include a peelablemoisture barrier foil 506 a that covers label 506. In order to activatelabel 506, the user simply removes foil 506 a.

Because label 506 relies on a color changing chemical reaction, the rateof reaction may also be dependent on temperature. Surprisingly, it hasbeen found that the temperature dependent variability of the colorchanging chemical reaction roughly matches the temperature dependentvariability of the shelf-life of many dental compositions. Thischaracteristic is advantageous as it allows the label to accuratelyindicate the remaining shelf-life of a dental composition that variesdue to differences in storage environments.

FIG. 4 illustrates an alternative system 600 including a syringe 604containing a dental composition 602. Syringe 604 includes a barrel 614and a plunger 616. A label 606 is disposed on barrel 614. Label 606includes a microchip 626 configured to measure lapsed time. Microchip626 is readable by an associated microchip reader so as to indicate to auser how much time remains in the shelf-life of composition 602 withincontainer 604. One such label including a microchip configured tomeasure lapsed time and an associated microchip reading device that maybe suitable is available from Clinisense Corporation located in LosGatos, Calif.

Microchip 626 may also be configured to account for differences intemperature, so as to integrate monitoring of both time and temperature.Such a configuration allows the label accurately indicate the remainingshelf-life of a dental composition that is stored in a variety ofenvironments.

The dental composition within the syringe or other container may have agiven shelf-life ranging from less than about a week to 2 years or more.Because of relative instability many mixed two-part dental compositionshave a relatively short shelf-life (e.g., 30 days or less). For examplesome two-part peroxide bleaching compositions may have a shelf-life ofabout 10-14 days after mixing, some disinfecting solutions may have ashelf-life of about a week or less, and some two-part dental primers mayhave a shelf life of about 30 days. Container systems includingactivatable time sensitive marking means according to the presentinvention are particularly suitable for use with such mixed dentalcompositions.

In addition, relatively stable single part dental compositions may havea shelf-life that is much longer (e.g., from 6 months up to 2 years ormore). Such compositions often include an expiration date stamped orprinted on the container, which can be difficult to identify. The timesensitive marking means of the present invention provides a more easilyused system including a more easily identifiable label, eliminating theneed for the user to search for a difficult to find date stamp. Thecontainer systems of the present invention may also be used with suchcompositions.

III. Exemplary Pre-Dosed, Pre-Packaged Mixing Systems

In an alternative embodiment, an initially separate two-part dentalcomposition may be provided as a pre-dosed, pre-packaged mixing solutionin which the dental practitioner is able to record a mixing and/orexpiration date of the less stable mixed composition on the mixingsystem itself. Providing a pre-dosed, pre-packaged mixing systemadvantageously eliminates any need for the dental practitioner tomeasure the required quantities of each component prior to preparing thetwo-part composition. In addition to being convenient, because thepre-dosing is done during manufacture, it is advantageously accomplishedwith a greater degree of precision and accuracy. This reduces oreliminates the possibility of mistakes or errors in the measuredquantities of each component affecting the required ratio of the firstcomponent relative to the second component. This is particularly helpfulas errors in the mixing ratio may drastically affect the actualshelf-life of the mixed composition. For example, a mixed dental primingcomposition may have a nominal shelf-life of about 30 days after mixing,but because of a small error (e.g., ±10%) in mixing ratio, the actualshelf-life of the composition may be greatly reduced (e.g., to less than15 days). If the composition is used after its actual expiration butbefore the nominal expiration, the composition will be ineffective,resulting in waste and frustration for both the dental practitioner andpatient. In other words, the indicated expiration date is much moremeaningful in the context of a pre-dosed, pre-packaged mixing system ascompared to any other system where individual measurement of one or moreof the components is required.

FIG. 5A illustrates an exemplary syringe-in-syringe mixing system 750including a pre-dosed, pre-packaged quantity of first and secondcomponents 760 a and 760 b, respectively. Components 760 a and 760 b mayboth be liquids, or one component may comprise a powder, as dictated bythe chemistry of the particular two-part composition. Mixing system 750includes a first plunger 752, a second hollow plunger 758, and a syringebarrel 762. First plunger 752 includes an elongate stem 754 with asealing plug 756 disposed at the distal end of stem 754. A lockingstructure 755 may be disposed near proximal end of stem 754. Lockingstructure 755 and its function will be described in further detailbelow. Plug 756 forms a seal against an interior surface of secondhollow plunger 758, within which first plunger 752 is slidably disposed.A first component 760 a is contained within a first chamber 758′ definedby second hollow plunger 758. Second hollow plunger 758 isconcentrically and slidably disposed within syringe barrel 762, whichdefines a second chamber 762′ in which is contained a second component760 b. A cap 764 may be coupled to a distal end of syringe barrel 762,which can be removed and/or replaced with a dispensing tip fordispensing after mixing the two-part composition.

Referring to FIGS. 5B and 5C, second hollow plunger 758 includes a wall766 that defines an internal chamber 758′ which contains a firstcomponent 760 a. Second hollow plunger 758 also includes a secondsealing plug 768 having a rupturable membrane 770 or other separationmeans (e.g., a duck bill or other type valve) at a distal end of secondhollow plunger 758, and a flange 772 at a proximal end of second hollowplunger 758. Rupturable membrane 770 seals off the distal end of secondhollow plunger 758, separating first component 760 a from the secondcomponent 760 b contained within the syringe barrel 762 (see FIG. 5A)until the user intentionally ruptures membrane 770 (or otherwise forcesfirst component 760 a through the separation means), causing firstcomponent 760 a to be forced into syringe barrel 762, where the twocomponents are mixed together. As seen in FIG. 5C, rupturable membrane770 initially seals off a distal end of second hollow plunger 758. Thedistal portion of second hollow plunger 758 over which sealing plug 768is fitted advantageously includes an enlarged annular ridge 774 thatprevents plug 768 from being separated from second hollow plunger 758during rupture of rupturable membrane 770.

Sealing plug 768 and rupturable membrane 770 may advantageously beformed of a thermoplastic elastomer (TPE) material, which advantageouslyprovides an excellent seal against an interior surface of syringe barrel762, while also providing a desired strength to rupturable membrane 770.Advantageously, the system may be configured so that the force requiredto rupture membrane 770 is approximately equal to the force required toinsert and engage the locking structure 755 of first plunger 752 intosecond hollow plunger 758. Such a configuration advantageously providesa smooth and continuous movement and feel during use of the system asfirst plunger 752 is pressed into second hollow plunger 758, rupturingmembrane 770 and locking first plunger 752 into second hollow plunger758.

Rupturable membrane 770 preferably has a thickness ranging from about0.0005 inch to about 0.04 inch, more preferably from about 0.002 inch toabout 0.025 inch, and most preferably from about 0.005 inch to about0.015 inch. Of course, the actual thickness of rupturable membrane 770will depend on the strength and other physical properties of thematerial from which it is formed, along with the configuration anddesired level of force required to break the membrane 770 and/or engagethe optional locking structure 755. One particularly suitable materialfrom which to form sealing plug 768 and rupturable membrane 770 isENGAGE, a TPE material sold by DuPont-Dow Elastomers located inWilmington, Del.

FIG. 6 illustrates an alternative syringe-to-syringe mixing system 850including a pre-dosed, pre-packaged quantity of first and secondcomponents. Mixing system 850 includes a first plunger 852, a firstsyringe barrel 858, a second plunger 852 a and a second syringe barrel862. First and second plungers 852 and 852 a may be identical, eachincluding an elongate stem 854, 854 a with a sealing plug 856, 856 a,respectively, formed at the distal end of stems 854, 854 a. Each ofplugs 856, 856 a forms a seal against an interior surface of syringebarrels 858 and 862, respectively, within which each of plungers 852,852 a is slidably disposed.

First syringe barrel 858 defines an internal first chamber 858′ in whichis contained a pre-dosed, pre-packaged quantity of first component 860a. Similarly, second syringe barrel 862 defines an internal secondchamber 862′ in which is contained a pre-dosed, pre-packaged quantity ofsecond component 860 b. Separation means (e.g., a rupturable membrane,duck bill valve, or other type valve) is disposed (not shown) betweenfirst chamber 858′ and second chamber 862′ so as to initially separatefirst and second components 860 a and 860 b during storage and prior touse, as any premature mixing may result in a partially mixed, lessstable composition, which quickly becomes ineffective and useless. Anexample of such separation means is the plug and rupturable membraneillustrated in conjunction with FIGS. 5B and 5C. In another example, theseparation means may comprise a small film of rupturable polymeric orother material (e.g., similar to SARAN wrap) stretched or otherwisedisposed over the distal end of one or both of syringe barrels 858 or862, which acts to initially separate chamber 858′ from 862′.

In order to mix the two-part composition, the user presses one of theplungers (e.g., first plunger 852) in, so as to force the componentcontained within the associated syringe barrel (e.g., first syringebarrel 858) through a rupturable membrane or other separation means andinto the other syringe barrel (e.g., second syringe barrel 862). Inorder to further mix the components so as to form a homogeneous mixture,the other plunger (e.g., second plunger 852 a) may then be pressed in,forcing the intermingled first and second components back into the othersyringe barrel (e.g., first syringe barrel 858). The plungers may bealternatingly pressed as many times as needed (e.g., about 3-10 times)so as to cycle the two-part composition back and forth, effectinghomogeneous mixing.

IV. Exemplary Methods of Use

In one exemplary method of use, a dental composition having a givenshelf-life is provided. For example, the dental composition may comprisea mixed composition formed by mixing together initially separatecomponents in a syringe-to-syringe mixing device or other suitablemixing apparatus. A container including activatable time sensitivemarking means disposed on or within the container is also provided. Thecontainer may comprise a syringe of the syringe-to-syringe mixingapparatus such that the dental composition may be contained within thesyringe or other container. Alternatively, the dental composition may beintroduced into the container (e.g., a syringe) including an activatabletime sensitive marking means disposed on or within the container.

The time sensitive marking means may be activated when needed so as tobegin to indicate the remaining shelf-life of the composition. Typicallythe time of activation will coincide with an event which affects theshelf-life of the composition (e.g., mixing initially separatecomponents to form the dental composition or opening a container toexpose the dental composition to air or light). The time sensitivemarking means indicates how much time has lapsed since activation,indicating to the user whether the dental composition is usable or not.

The dental practitioner identifies whether the given shelf-life of thecomposition is greater than or less than the time lapsed sinceactivation. If the lapsed time is less than the given shelf-life, thenthe dental practitioner may dispense and use the dental composition. Ifthe given shelf-life is less than the time lapsed since activation, thenthe dental practitioner may discard the composition or system. Thecontainer and activatable time sensitive marking means may be relativelyinexpensive, allowing the user to discard the entire system once thedental composition has expired.

FIGS. 7A-7D illustrate an alternative method for indicating shelf-lifeemploying the exemplary pre-dosed, pre-packaged syringe-in-syringemixing system 750 of FIG. 5A. A syringe-to-syringe mixing system (e.g.,mixing system 850 of FIG. 6) may alternatively be used according to asimilar method to provide a dental practitioner with an easy to usemixing solution that indicates shelf-life of the less stable mixeddental composition. Advantageously, such systems provide a pre-dosed andpre-packaged system that may be used for mixing, dispensing, and storingthe mixed two-part composition. Furthermore, such systems provide apre-dosed, pre-packaged mixing solution in which the two components arepre-measured in the correct quantities for mixing a desired quantity ofthe two-part composition. Pre-dosing and pre-packaging the componentsreduces the work required of the dental practitioner, and reduces thepossibility that a user (particularly an inexperienced one) will make amistake in measuring quantities of the components (i.e., affecting themixing ratio), which may drastically alter the effectiveness and/orshelf-life of the mixed composition. In addition, the pre-packagedamount of each component may advantageously be sufficient (and no more)so as to provide a quantity of the mixed two-part composition that wouldtypically be used up by the dental practitioner within the specificshelf-life of the mixed, unstable two-part composition so as to reducewaste of any unused composition. For example, the amounts of eachcomponent may be such as to prepare between about 0.05 and about 1 mL,more typically between about 0.1 and about 0.8 mL, and most typicallybetween about 0.2 and about 0.6 mL of the less stable mixed dentalcomposition. The actual amount of mixed dental composition depends onthe particular composition (e.g., a dental primer, a peroxide or othertwo-part bleaching composition, or a disinfecting solution), asdifferent compositions are used more or less frequently in variousamounts, and each composition also has its own particular shelf life(e.g., less than about 90 days, less than about 30 days, or less thanabout 2 weeks). Providing no more than a quantity sufficient for theshelf-life of the composition is advantageous as the amount mixed isused up within the particular shelf life of the composition, whichreduces waste.

As seen in FIGS. 7B-7C, the user presses first plunger 752 into secondhollow plunger 758 so as to compress first component 760 a. Once asufficient force is applied, first component 760 a is expressed underpressure from second hollow plunger 758 into syringe barrel 762 where itmixes with second component 760 b, which may occur through rupture ofrupturable membrane 770 or breaking, opening, and/or parting of someother separation means.

Rupturable membrane 770, a valve, or other separation means mayadvantageously be configured to only pass first component 760 a formixing with second component 760 b under a pressure sufficiently high tocause jetting of the first component into the second component (e.g., soas to create turbulence sufficient to homogeneously mix the twocomponents together). The system may advantageously be configured suchthat a force required to rupture membrane 770 is approximately equal toa force required to insert and lock locking structure 755 into secondhollow plunger 758. In use, locking structure 755 becomes inserted intosecond hollow plunger 758, where the locking structure 755 biasesagainst the inside surface of second hollow plunger 758. Such anoptional locking structure results in a configuration such that whenfirst plunger 752 is fully inserted into second hollow plunger 758,locking structure 755 extends distally into second hollow plunger 758,past flange 772. Locking structure 755, illustrated as comprising anannular interlock ring, causes the formation of an indentation or groovewithin the inside wall of second hollow plunger 758. Annular interlockring locking structure 755 resides in the formed groove, preventing, orat least inhibiting, pull out of first plunger 752 once fully insertedinto second hollow plunger 758. Additional locking structures and mixingsystems are disclosed in U.S. patent application Ser. No. 11/414,964,filed May 1, 2006, already incorporated by reference, and in a U.S.patent application bearing attorney docket number 7678.988.1, filed thesame day as the present application, which is also incorporated byreference in its entirety.

As seen in FIG. 7C, the user is able to record the mixing and/orexpiration date 776 on a surface of mixing system 750 either immediatelyprior to or immediately subsequent to fully pressing first plunger 752into second hollow plunger 758. As illustrated, the user may write amixing and/or expiration date directly onto the exterior surface.Advantageously, a designated exterior writing surface (e.g., at least aportion of the syringe barrel) may be coated or otherwise comprise atextured surface comprising a TPE material, which provides an improvedwriting surface on which a ball-point pen or similar writing device canbe used (i.e., the TPE material acts to “grab” the writing end of aball-point pen). Of course a felt-tip pen, marker, or even a pencil mayalso be used. Alternatively, the date may be written on a label (e.g., apressure sensitive adhesive label) which is adhered to the exteriorsurface of the syringe barrel 762. Advantageously, the dentalpractitioner may apply a transparent or translucent adhesive protectivecovering (e.g., SCOTCH tape) over the recorded date so as to protect thedate from damage or alteration (e.g., by contact with a solvent, bysmearing, or rubbing which may otherwise wear away the date or render itillegible).

Advantageously, the mixing system 750 may be used for storing anddispensing the mixed composition, so that no transfer to a separatedispensing device is required. FIG. 7D illustrates the system 750 with adispensing tip 764′ coupled at a distal end of barrel 762 so as to allowthe user to dispense the mixed two-part composition 760. As illustrated,composition 760 may be dispensed onto a pad for subsequent application(e.g., with a brush tool). Alternatively composition 760 may bedispensed directly onto a tooth or other surface, depending on thepreference of the user.

The inventive method advantageously provides a simple, ready to usesystem in which the two-part composition is provided in a pre-dosed,pre-packaged, ready to mix and use configuration. In addition, the useris able to record the mixing and/or expiration date directly onto asurface of the mixing system for later reference, indicating to thedental practitioner whether the less stable mixed dental composition hasexpired or not. The system and associated method reduces or eliminatesthe possibility of mistakes or errors in the measured quantities of eachcomponent affecting the required mixing ratio and actual shelf-life ofthe mixed composition.

It will be appreciated that the present claimed invention may beembodied in other specific forms without departing from its spirit oressential characteristics. For example, although several specificembodiments of activatable time sensitive marking means have beendescribed, it is to be understood that any structure that can bedisposed on or integrated into the container with the ability toindicate time lapsed since activation may be used. The describedembodiments are to be considered in all respects only as illustrative,not restrictive. The scope of the invention is, therefore, indicated bythe appended claims rather than by the foregoing description. Allchanges that come within the meaning and range of equivalency of theclaims are to be embraced within their scope.

1. A syringe system for mixing and for recording the mixing date topermit monitoring of the shelf life of a mixed two-part dentalcomposition, the syringe system comprising: a first pre-dosedcomposition pre-packaged so as to be contained in a first syringe havinga barrel with a first plunger slidable within the first barrel; a secondpre-dosed composition pre-packaged so as to be contained in a secondsyringe having a barrel, with a second plunger slidable within thesecond barrel, and the separate compositions each having a shelf lifesignificantly greater than the shelf life of the two compositions afterthey are mixed; the first and second plungers being operable so that byfirst sliding the first plunger into the first syringe barrel the firstpre-dosed composition is introduced into the second syringe barrel sothat it contacts the second pre-dosed composition, the two compositionsthereafter being either further mixed using one or both syringe barrels,or else applied in a dental procedure by expressing the mixed contentsfrom the second syringe barrel; and an activatable label disposed on oneof the first or second syringes and having a material which, whenexposed by pealing back a cover upon mixing the two compositions, beginsto change from a first to a second color as a function of time tothereafter provide a visual indication which automatically changes overtime, the second color indicating elapsed time from when the twocompositions were mixed so that the shelf life of the mixed compositionsis easily ascertainable from the visual indication.
 2. The system ofclaim 1, wherein the rate at which the material of the label changescolor from the first to the second color is also a function oftemperature so that the change to the second color will be delayed whenthe mixed dental compositions are refrigerated to extend the shelf lifeof the mixed dental compositions.
 3. The system of claim 1 wherein thefirst syringe barrel is connected end-to-end with the second syringebarrel so as to form a syringe-to-syringe mixing system.
 4. The systemof claim 1 wherein the first syringe barrel fits within the secondsyringe barrel so that the first syringe barrel also functions as theplunger for the second syringe barrel, thus forming a syringe-in-syringemixing system.
 5. The system of claim 4 wherein an outlet end of thefirst syringe barrel comprises a rupturable membrane so that when theplunger is pushed into the first syringe barrel, the pre-dosed dentalcomposition packaged within the first syringe barrel will be expelledunder pressure sufficient to create turbulence, into the second syringebarrel, thus mixing the two dental compositions in the second syringebarrel.
 6. The system of claim 4 wherein the plunger of the firstsyringe barrel comprises a locking structure so that when the plunger ispushed into the first syringe barrel a sufficient distance, the syringeplunger inhibits the plunger from thereafter being withdrawn from thefirst syringe barrel.
 7. The system of claim 6 wherein the lockingstructure comprises an annular ring formed on a circumference of theplunger of the first syringe barrel which cooperates with acorresponding groove formed inside the first syringe barrel forreceiving the annular ring when the plunger is pushed far enough intothe first syringe barrel.
 8. A syringe system for mixing and forrecording the mixing date to permit monitoring of the shelf life of amixed two-part dental composition, the syringe system comprising: afirst pre-dosed dental composition pre-packaged so as to be contained ina first syringe having a barrel with a first plunger slidable within thefirst barrel; a second pre-dosed dental composition pre-packaged so asto be contained in a second syringe having a barrel, with a secondplunger slidable within the second barrel, and the separate compositionseach having a shelf life significantly greater than the shelf life ofthe two compositions after they are mixed; the first and second plungersbeing operable so that by first sliding the first plunger into the firstsyringe barrel the first pre-dosed composition is introduced into thesecond syringe barrel so that it contacts the second pre-dosedcomposition, the two compositions thereafter being either further mixedusing one or both syringe barrels, or else applied in a dental procedureby expressing the mixed contents from the second syringe barrel; and anactivatable label having a microchip readable by an associated microchipreader which indicates to a user the time lapsed since mixing the twodental compositions.
 9. The system of claim 8 wherein the microchip isconfigured to account for differences in temperature so that the lapsedtime recorded by the microchip will be delayed when the mixed dentalcompositions are refrigerated to extend the shelf life of the mixeddental compositions.
 10. The system of claim 8 wherein the first syringebarrel is connected end-to-end with the second syringe barrel so as toform a syringe-to-syringe mixing system.
 11. The system of claim 8wherein the first syringe barrel fits within the second syringe barrelso that the first syringe barrel also functions as the plunger for thesecond syringe barrel, thus forming a syringe-in-syringe mixing system.12. The system of claim 11 wherein an outlet end of the first syringebarrel comprises a rupturable membrane so that when the plunger ispushed into the first syringe barrel, the pre-dosed dental compositionpackaged within the first syringe barrel will be expelled under pressuresufficient to create turbulence, into the second syringe barrel, thusmixing the two dental compositions in the second syringe barrel.
 13. Thesystem of claim 11 wherein the plunger of the first syringe barrelcomprises a locking structure so that when the plunger is pushed intothe first syringe barrel a sufficient distance, the syringe plungerinhibits the plunger from thereafter being withdrawn from the firstsyringe barrel.
 14. The system of claim 13 wherein the locking structurecomprises an annular ring formed on a circumference of the plunger ofthe first syringe barrel which cooperates with a corresponding grooveformed inside the first syringe barrel for receiving the annular ringwhen the plunger is pushed far enough into the first syringe barrel.